JP2822715B2 - Laser trimming method and apparatus for film resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for laser trimming of a film resistor included in an electric circuit device such as a hybrid integrated circuit.

[0002]

2. Description of the Related Art A so-called laser trimming method in which a coherent laser beam is radiated onto a thick film resistor in a pulsed manner to form a cut groove by sequentially overlapping hot spots is a well-known technique in function trimming of a hybrid IC. In function trimming, the output voltage of an electric circuit is measured each time a predetermined number of hot spots are formed on a film resistor by a laser beam, and a laser beam is repeatedly projected on the film resistor until the output voltage reaches a predetermined value.

[0003]

By the way, various wavelengths of light are included in the laser beam itself or the radiation emitted from the film resistor when trimmed. When a monolithic IC is placed near the film resistor,
Certain wavelengths of light can adversely affect monolithic ICs. For example, when a latch circuit is included in a monolithic IC, a light beam of a specific wavelength enters the monolithic IC, and the latch circuit malfunctions.
Output voltage transmission may be interrupted. In this case, it is impossible to confirm the trimming state of the film resistance.
When the output voltage becomes low, the control device determines that trimming is insufficient, and continues to form a cut groove for the film resistance, which may result in a defective film resistance.

Accordingly, an object of the present invention is to provide a method and an apparatus capable of performing laser trimming accurately.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention measures the output of an electric circuit device and, based on the measurement result, changes the film resistance contained in the electric circuit device with a laser beam. In the trimming method, the input voltage of the electric circuit device is switched to a level at which the electric circuit device does not malfunction based on the laser beam, and the laser beam is projected on the film resistor.After that, the output of the electric circuit device is output. The present invention relates to a method of laser trimming a film resistor, which provides an input voltage at a level that can be measured to the electric circuit device.

When the electric circuit device includes a latch circuit, it is desirable that the latch circuit be reset (latch released) between the laser beam projection period and the measurement period.

The invention relating to the above-described apparatus for performing trimming is directed to an apparatus for laser-trimming a film resistor included in an electric circuit device, wherein a measuring power supply is provided between the measuring power supply and an input terminal of the electric circuit apparatus. A connected input voltage control circuit, a measuring device connected to an output terminal of the electric circuit device, a laser beam projecting device for projecting a laser beam on the film resistor, the input voltage control circuit, and the measuring device And a control device for controlling the laser beam projection device, and the control device generates a first control pulse having a predetermined period, and sets the same period as the predetermined period or a period that is an integral multiple of the predetermined period. And the second control pulse is generated at a different time from the first control pulse. Configured to project a laser beam onto the film resistor in response to the measurement, wherein the measurement device is configured to measure an output of the electrical circuit device in response to the second control pulse, The input voltage control circuit includes a switch that lowers an input voltage supplied from the measurement power supply to the electric circuit device for a predetermined time longer than a width of the first control pulse in response to the first control pulse. The present invention relates to a film trimming laser trimming device having a film resistance.

When the electric circuit device has a latch circuit, first, second and third control pulses are generated, and the latch circuit is reset by the third control pulse. Can be configured.

[0009]

According to the first and third aspects, it is possible to prevent malfunction of the electric circuit device based on the laser beam during the period when the laser beam is projected. According to claims 2 and 4, since the latch circuit is reset before the measurement,
The continuation of trimming due to an erroneous latch state can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method and an apparatus for laser trimming a thick film resistor of a hybrid integrated circuit device according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a control circuit 1 comprising a hybrid integrated circuit of a switching regulator and this laser trimming device. The laser trimming device includes a DC power supply 2, an input voltage control circuit 3, a laser beam projecting device 4, a measuring device 5, and a control device 6.

The DC power supply 2 supplies the measured voltage to the control circuit 1 to be measured.
Give to. The input voltage control circuit 3 includes transistors 7, 8,
9, resistors 10 and 11, a capacitor 12, and a monomultivibrator or MMV 13. The transistor 7 is connected between the power supply 2 and the input power supply terminal 14 of the measured circuit 1 via a resistor 10. The base of the transistor 7 is connected to the ground via the resistor 11 and the transistor 8. The capacitor 12 is connected between the output terminal of the resistor 10 and the ground. The transistor 9 is connected to the capacitor 12 in parallel. MM
V13 is connected to the bases of the two transistors 8,9.

The control circuit under test 1 is a monolithic IC 1
5. Includes resistors R1, R2, etc. to be trimmed.
The measuring device 5 is connected to the output terminal of the control circuit under test 1,
The output of the control circuit under test 1 is measured.

The control device 6 supplies a first control pulse to the laser beam projecting device 4 on a line 6a, and the MMV 13
To the trigger signal. Also, the control device 6 is connected to the line 6b
Gives a second control pulse to the measuring device 5. FIG.
The operation of this device and the trimming method will be described later in detail.

The control circuit under test 1 shown in FIG. 1 is a circuit for controlling ON / OFF of the FET switch Q1 of the switching regulator shown in FIG. The switching regulator shown in FIG. 2 includes a DC power supply 20, primary, secondary and tertiary and tertiary windings N1, N2, and N3 of a transformer 21, a rectifying and smoothing circuit 22 in addition to the FET switch Q1 and the control circuit 1. , A voltage detection and control circuit 23, a starting resistor 24, an auxiliary power diode 25, and a capacitor 26. Primary winding N
The series circuit of 1 and the FET switch Q1 is connected to the power supply 20. The secondary winding N2 is connected to a rectifying and smoothing circuit 22, and a load 29 is connected between the output terminals 27 and 28. The control circuit 1 is a circuit for forming a PWM pulse for turning on / off the FET switch Q1, and this output terminal 16 is connected to the gate of the FET switch Q1. The ground terminal 17 of the control circuit 1 is connected to the ground terminal of the power supply 20. The voltage control signal input terminal 18 of the control circuit 1 is connected to the voltage detection and control circuit 23. The voltage detection and control circuit 23 is a well-known circuit that detects a voltage between the output terminals 27 and 28 and compares the detected voltage with a reference voltage by error amplification. To obtain the power supply voltage of the control circuit 1, a diode 25 and a capacitor 26 are connected to the tertiary winding N3. The power supply terminal 14 of the control circuit 1 is connected to a capacitor 26. Note that the capacitor 26 is charged via the resistor 24 at the time of startup.

FIG. 3 shows a control circuit 1 having a hybrid integrated circuit configuration. In the control circuit 1, a monolithic IC 30 integrated with a semiconductor is arranged on a common insulating substrate (not shown), thick film resistors R1 and R2 are arranged, and capacitors C1 and C2 are arranged. It is constituted by that.

The monolithic IC 30 includes a pulse generator 3
1, an output cutoff switch 32, a drive circuit 33, an overvoltage detection circuit 34, an overheat detection circuit 35, a trigger circuit 36, an OR gate 37, a latch circuit 38, a constant voltage conversion circuit 39, A power supply terminal 40, an output terminal 41,
An external trigger terminal 42 and three connection terminals 43, 44, 4
And 5. The monolithic IC 30 includes more terminals and circuits, but only the main ones are shown here.

The pulse generating circuit 31 is connected to the output terminal 16 via a driving circuit 33 and a terminal 41. The oscillation output cutoff switch 32 is connected between the output line of the pulse generator 31 and the ground. The output terminal 16 is connected to the FET switch Q1 of FIG. 2 when forming a switching regulator. To control the width of the output pulse of the pulse generator 31, the pulse generator 31 is connected via connection terminals 44, 45 to the first and second capacitors C1, C2.
Connected to 2. The upper terminal of the capacitor C1 is connected to a constant voltage circuit 39 via a first resistor R1, connected to a control signal input terminal 18 via a resistor R3, and further connected to a second terminal via a diode D1. It is connected to the capacitor C2.

The overvoltage detection circuit 34 is connected to the input power supply terminal 40. In this embodiment, the auxiliary power supply voltage is obtained based on the tertiary winding N3 of the transformer 21, and the voltage obtained in the tertiary winding N3 is rectified by the diode 25 during the OFF period of the FET switch Q1, so that the voltage corresponding to the load voltage The obtained voltage can be obtained at the input power supply terminal 14 through the tertiary winding N3. Therefore, the overvoltage detection circuit 34 can detect the overvoltage by comparing the voltage of the input power supply terminal 14 with the reference voltage indicating the overvoltage level by the comparator.

The overheat detection circuit 35 is configured to compare the output of a sensor for detecting the temperature of the IC 30 with a reference voltage.

The trigger circuit 36 is connected to an external connection terminal 46 via a terminal 42 of the IC 30. A signal is supplied to the external connection terminal 46 when the FET switch Q1 in FIG. 2 is turned off. The resistors R4 and R5 and the capacitor C3 are connected between the terminals 46 and 42.

The OR gate 37 is connected to the overvoltage detection circuit 34, the overheat detection circuit 35, and the trigger circuit 36, and outputs these (trigger signals) to the input terminal of the latch circuit 38.

A latch circuit 38 comprising an RS flip-flop latches the output of the OR gate 37, and controls the switch 32 to be turned on by this latch output (set output).
Cut off the pulse output. The reset terminal of the latch circuit 38 is connected to the reset trigger circuit 38a. The reset trigger circuit 38a is connected to the input power supply terminal 40, and generates a reset trigger signal in synchronization with the rise of the input power supply voltage.

When trimming the thick film resistors R1 and R2 of the control circuit 1, the control circuit 1 is connected to a trimming device as shown in FIG.
The first and second control pulses shown in FIG.
6b. The first control pulse shown in (A) has a frequency of 3 kHz, a period (1/3000 second) and a time t1.
, T4 and t7. The second control pulse shown in (B) has the same period and frequency as the first control pulse and is generated at times t3, t6, and t9. The point in time at which the second control pulse occurs is between the first control pulses. The first control pulse is supplied to the laser beam projector 4 and to the MMV 13. The laser beam projector 4 projects a laser beam on the thick film resistor R1 or R2 in response to the first control pulse to form a groove. The resistance value of the thick film resistor R1 or R2 increases in accordance with the number of laser beam projections in response to the first control pulse. The change in the resistance value of the thick film resistors R1 and R2 based on the projection of the laser beam is determined by the change in the output voltage of the control circuit 1. The power supply 2 is connected to the input power supply terminal 14 of the control circuit 1 in place of the capacitor 26 shown in FIG.
Are connected, the control circuit 1 operates similarly to the case of FIG. In FIG. 1, the voltage control signal input terminal 18
Is open, but a predetermined voltage may be applied here. The measuring device 5 samples a voltage obtained by smoothing the output pulse of the pulse generator 31 of FIG. 3 obtained from the output terminal 16 of the control circuit 1 based on a second control pulse shown in FIG. To the control device 6. The voltage obtained by smoothing the output pulse from the output terminal 16 increases every time the laser beam is projected as shown in FIG. The controller 6 determines whether or not the voltage sample value of FIG. 4E has reached a predetermined reference value. When the voltage sample value reaches the predetermined reference value, the control device 6 stops sending the first and second control pulses and terminates the trimming. .

In this embodiment, the input voltage is not continuously applied to the control circuit 1 shown in FIG. The MMV 13 generates an input voltage control pulse shown in FIG. 4C in response to the leading edge of the first control pulse shown in FIG. This input voltage control pulse has a width wider than the first control pulse and the laser beam projection time width. Transistors 8 and 9
Turns on in response to the output pulse of the MMV 13, and conversely, the transistor 7 turns off. As a result, the input voltage becomes zero volt during the periods t1 to t2, t4 to t5, and t7 to t8 as shown in FIG. At the same time, the charge of the capacitor 12 is released via the transistor 9. As a result, while the resistor R1 or R2 is being trimmed by the laser beam, the latch circuit 38 of FIG. Alternatively, the circuit of the latch input stage (such as the overheat detection circuit 35) malfunctions, and the latch circuit 38 is prevented from erroneously entering the latch state. When the output of the MMV 13 returns to a low level, the transistors 8 and 9 are turned off,
Conversely, transistor 7 is turned on. Since the capacitor 12 is connected to the output stage of the transistor 7, the input voltage gradually rises as shown in FIG. For this reason, it is possible to prevent a malfunction of the latch circuit 38 which is likely to occur due to a rapid rise. When the input voltage rises, a reset trigger pulse is generated from the reset trigger circuit 38a, and the latch circuit 38 is reset. Latch circuit 38
Is reset every time the laser beam is projected, a normal input voltage can be obtained at the time points t3, t6 and t9 of the generation of the second control pulse. As a result, the measurement of the output voltage based on the second control pulse is reliably achieved. Further, since the output control switch 32 of the pulse generator 31 is not turned on based on a malfunction of the latch circuit 38, trimming can be accurately achieved.

[0026]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) As shown in FIGS. 5A and 5B, the control device 6 generates the first and second control pulses in the same manner as in FIGS. ) Is generated between the first control pulse and the second control pulse, and the third control pulse is applied to the MMV 13 in FIG. 1 to generate the third control pulse as shown in FIG. The input voltage may be reduced in synchronization with this. In this case, the input voltage is recovered before the second control pulse is generated. (2) When the output frequency is set to a predetermined value by trimming the resistor R1 or R2, the output frequency may be converted into a voltage and it may be determined whether or not this is a reference value. (3) In FIGS. 4 and 5, the first control pulse and the second control pulse have the same period, but the period of the second control pulse is set to an integral multiple of the first control pulse. Is also good.
In this case, the cycle of the third control pulse in FIG. 5 can be made an integral multiple similarly to the second control pulse. (4) The switch 32 can be connected in series to the line. Further, the phase inversion output terminal (negative output terminal) of the latch circuit 38 can be connected to the switch 32. Further, the latch circuit 38 can be formed by a flip-flop other than the RS flip-flop.

[0027]

As is apparent from the above, according to the invention of each claim, it is possible to prevent the electric circuit from malfunctioning due to the laser beam or the radiation generated based on the laser beam, making it impossible to perform trimming.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a trimming device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a switching regulator using the control circuit of FIG. 1;

FIG. 3 is a block diagram showing a control circuit of FIG. 1 in detail.

FIG. 4 is a waveform diagram showing a state of each unit in FIG. 1;

FIG. 5 is a waveform chart for explaining a modification.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control circuit 2 power supply 3 input voltage control circuit 4 laser beam projection device 5 measuring device 6 control device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 17/22-17/24

Claims (4)

(57) [Claims] 1. A method of measuring an output of an electric circuit device and trimming a film resistor included in the electric circuit device with a laser beam based on the measurement result, wherein the input voltage of the electric circuit device is The electric circuit device is switched to a level at which the electric circuit device does not malfunction based on the laser beam, and the laser beam is projected on the film resistor. Thereafter, the input voltage at a level at which the output of the electric circuit device can be measured is changed to the electric circuit device. Laser trimming method for a film resistor. 2. A film resistance so that a predetermined output signal can be obtained from an electric circuit device including a latch circuit for controlling transmission of an output signal and a film resistance having a predetermined relation to the output signal. In the method of trimming with a laser beam, a laser beam is intermittently projected on the film resistor to perform trimming, an output signal of the electric circuit device is intermittently measured to determine a trimming state, and the laser beam is projected. A laser trimming method for a film resistor, wherein the latch circuit is reset between a period and a measurement period of the output signal. 3. An apparatus for laser trimming a film resistor included in an electric circuit device, comprising: a measuring power source; an input voltage control circuit connected between the measuring power source and an input terminal of the electric circuit device; A measuring device connected to an output terminal of the electric circuit device, a laser beam projecting device for projecting a laser beam onto the film resistor, controlling the input voltage control circuit, the measuring device, and the laser beam projecting device The control device generates a first control pulse having a predetermined period, and generates a second control pulse having the same period as the predetermined period or an integral multiple of the predetermined period. Wherein the laser beam projection device projects a laser beam onto the film resistor in response to the first control pulse. The measuring device is configured to measure an output of the electric circuit device in response to the second control pulse, and the input voltage control circuit is configured to measure the first control pulse. A switch for setting an input voltage supplied from the measurement power supply to the electric circuit device to a low level for a predetermined time longer than the width of the first control pulse in response to Laser trimming device. 4. An apparatus for laser trimming a film resistance of an electric circuit device including a latch circuit for controlling transmission of an output signal and a film resistance having a predetermined relation to the output signal, comprising: a measuring power supply; An input voltage control circuit connected between the measurement power supply and an input terminal of the electric circuit device, a measurement device connected to an output terminal of the electric circuit device, and a device for projecting a laser beam on the film resistor. A laser beam projecting device, and control for generating first, second and third control pulses intermittently and at different times to control the input voltage control circuit, the measuring device and the laser beam projecting device. And the laser beam projection device is configured to project a laser beam onto the film resistor in response to the first control pulse; The measuring device is configured to measure an output signal of the electric circuit device in response to the second control pulse, and the input voltage control circuit is configured to measure the output signal based on the second control pulse. A laser trimming device for a film resistor, wherein a change in the input voltage that can reset the latch circuit beforehand occurs in response to the third control pulse.